Despite a marked increase in the availability of gambling opportunities on Native American lands and in surrounding geographic areas, there is a lack of research examining the effects of gambling availability and sociodemographic factors on the frequency of gambling, problem gambling and co-occurring alcohol and other drug abuse among Native Americans in the U.S. This revised R21 application, Ecological & Sociocultural Influences on Native American Gambling & Alcohol Use, is a pilot study to develop and test culturally-sensitive epidemiologic measures and methods to determine the correlates of gambling, problem gambling and co-occurring alcohol and other drug use among a diverse sample of Native Americans in the U.S. This pilot study will provide the basis for a larger, representative national study of gambling and substance use among Native Americans in the U.S. Telephone interviews will be conducted with 250 Native American adults aged 18 years and older from geographic areas across the U.S. with high densities of Native Americans. The survey will use a targeted U.S. sample of landline and cell phone numbers of Native Americans. Place of residence will be geo-coded and linked with U.S. census data which is available for tribal- designated statistical areas and for Native American reservations and off-reservation trust lands. In addition, the measures of gambling and substance use will be comparable to our ongoing NIH-funded study of gambling and substance use among the general population of adults in the U.S. Based on social ecology theory, the availability of gambling opportunities using geo-coded addresses of gambling facilities on and off reservations will be linked with gambling behaviors. Ecological factors will also include census data (tribal and non-tribal census block data) describing the degree of neighborhood/geographic-area disadvantage. Using problem behavior theory, this study will examine the co-occurrence of frequent gambling and alcohol and other drug use among Native Americans by combining this sample of Native Americans with the projected 150 Native Americans to be interviewed in the ongoing national survey of gambling. Unlike the general population survey, this study of Native Americans will develop and test measures pertinent to traditional Native American culture which is hypothesized to be a protective factor for problem gambling and alcohol abuse among Native Americans. The ultimate goal of this pilot study is to serve as the basis for a larger, representative U.S. study of gambling and substance use among Native Americans. This research is needed to develop targeted prevention and intervention programs for Native Americans in the U.S.